This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Despite the recent successes in structural characterization of membrane proteins by X-ray crystallography and solution NMR spectroscopy, these studies remain a challenge due to the inherent insolubility and difficulties in crystallization of many membrane-associated proteins. As a result, our knowledge about the architecture and function of membrane proteins remains sparse. In particular, structural changes associated with activation of peripheral membrane proteins by non-substrate lipids, which are critical for the enzymatic activity of these proteins, are not understood at the atomic level because of a lack of experimental methods to probe specific protein-lipid interactions. In this pilot project, we are developing new magic angle spinning solid-state NMR based methods to study the structure and function of peripheral membrane proteins. In particular, two- and three-dimensional experiments are established to probe lipid-protein interactions directly. These experiments are tested on a phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus thuringiensis. With the new methods in hand, the structural basis of the interfacial activation of PI-PLC can be examined. These efforts represent the first step toward our long-term goal to elucidate the structure and the mechanism of biomedically important human phospholipases.